JADGE
The computerised network, known as JADGE (Japan Aerospace Defense Ground Environment), is operated and maintained by the ASDF. It was originally developed in the early 1960s from the handover of USAF stations, and some of the equipment dates back to these origins (e.g. AN/FPS-20), and became operational in 1989. Generally located on coastal mountain tops, the radar systems afford the ASDF full coverage of the Japanese islands.
Coverage of Japan's Radar Network
The above map was recreated and adapted from a book by Toshiyuki Shikata, retired GSDF Lt. General, Professor at Teikyo University and security advisor to the Governor of Tokyo, Shintaro Ishihara – a clear authority on Japanese military issues. It shows the location of ASDF sub-bases with radar installations, and their overlapping coverage at 50, 75, 130 and 200 nautical miles (note the map in the book, and the one above, is simply an approximation). What is clear is that at 200NM, Japan is fully covered by its air defense radars, although the full range of the newer installations, and limitations of the older ones are not included (they are presumably kept secret for national security).
The early-warning installations provided by JADGE also support electronic and electro-magnetic measurement intelligence (ELINT/ESM) collection stations – near Wakkanai, Nemuro, Okushiri, Seburijima, Fukuejima, Misawa and Miyakojima. There are reports of communications intelligence (COMINT) collection stations near Takaoyama, Fukuejima and Miyakojima.
Composition of Radar Network
The 28 integrated facilities around Japan that comprise JADGE are coordinated via the US-developed Link 16 Joint Tactical Information Distribution System (JTIDS)/Multifunctional Information Distribution System (MIDS) at ASDF Air Defense Command, currently being transferred to Yokota AFB from Fuchu Air Station.
The ASDF operates seven J/FPS-2 static three-dimensional radars, first installed in 1979 with a range of 200 km (approx. 100 nautical miles).
A further seven facilities operate the recently upgraded J/FPS-3A, a three-dimensional phased array radar with a search range of around 370 km (approx. 200 nautical miles) and height-finding at 150 km (approx. 80 nautical miles).
The most modern additions to the network are the six J/FPS-4 sites and the five J/FPS-5 sites, while older AN/FPS-20 and AN/FPS-6 radars operate at four sites (one per Air Defense Force).
Below is a break down of the types of radars at each installation, as gleaned from the Japanese ‘Radar Site’ page over at Wikipedia.
http://jsw.newpacificinstitute.org/?p=4011
